Belching cattle apocalypse menace sniffed in cowpats

Cattle experts in Blighty and Ireland say they have discovered a much better way of finding out just how much methane is emitted by the world's cows - and thus, how much of a greenhouse-gas problem cattle actually are - by carrying out a detailed analysis of cowpats.

Methane, though emitted from agriculture, industries, people etc in relatively small quantities compared to CO2, is of concern as it has 25 times the greenhouse effect in the atmosphere. Its presence is accounted for in most climate models, but the truth is that the boffinry community doesn't really know with any great accuracy how much methane cows emit.

"We're quite good at measuring man-made CO2 emissions, but techniques to measure the animal production of methane – a much more potent greenhouse gas – have serious limitations," explains agro-scientist Dr Fiona Gill.

Gill has been working together with the aptly-named Dr Ian Bull on a method of determining cattle methane emissions by examining their poo. Specifically the scientists consider that the amount of a specific compound known as archaeol can be used as a good indicator of how much methane various kinds of animals are generating: not just cows but sheep and deer as well. Though cows in particular are thought to emit most of their methane by belching rather than from the back end, the level of archaeol should still reflect the total.

"We initially detected archaeol in the faeces of several foregut fermenters including camels, cows, giraffes, sheep and llamas," says Bull. The scientists then went on to nail down the relationship between archaeol and methane emissions specifically in cows, feeding groups of cattle on different diets so as to vary their methane output.

The amount of methane emitted was then measured and correlated with the archaeol in the resulting cowpats, apparently indicating that yes indeed, archaeol levels are a good indicator for methane emissions. "We can use this along with information on diet and animal population numbers to estimate their total contribution to global methane levels," says Gill.

The research also supports the idea - advanced in various previous studies - that cattle methane emissions can be significantly affected/controlled by means of altering their diet.

The new cattle crap research can be read here in the journal Animal Feed Science and Technology. ®